CVE-2026-15571Network attack vector

Account takeover via predictable linking hash

Published Aug 18, 2026 · Updated Aug 20, 2026

Authentication bypass in Red Hat build of Keycloak allows remote authenticated users to take over accounts via forged linking URLs. The legacy client-initiated account-linking endpoint at /realms/{realm}/broker/{provider}/link accepts a CSRF hash derived from SHA-256(nonce + userSessionId + clientId + providerAlias), and Red Hat states that a registered OIDC client can obtain or choose each input and predict the hash. Exploitation requires control of a registered OIDC client and user interaction to complete authentication, after which the attacker can sign in as the victim with the linked external identity.

CVSS severity7.3
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Red Hat build of Keycloak allows remote authenticated users to take over accounts via forged linking URLs. The legacy client-initiated account-linking endpoint at /realms/{realm}/broker/{provider}/link accepts a CSRF hash derived from SHA-256(nonce + userSessionId + clientId + providerAlias), and Red Hat states that a registered OIDC client can obtain or choose each input and predict the hash. Exploitation requires control of a registered OIDC client and user interaction to complete authentication, after which the attacker can sign in as the victim with the linked external identity.

The record

CVE
CVE-2026-15571
Published
Aug 18, 2026
Updated
Aug 20, 2026
Vendor
389 Directory Server
Product
Red Hat build of Keycloak
Classifications
CWE-341, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

389 Directory Server · Red Hat build of KeycloakAffected versions are unavailable in this record.

Published CVSS scores

7.3Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-341Predictable from Observable State
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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